The majority of thrust transmitting members are in the form of balls adapted to be clamped in female receptables to exert forward or reverse thrust on a load carrying vehicle. Several sizes of balls are employed dependent on the load to be transported. On occasion it is common practice for a pulling vehicle to engage and pull loads of varying sizes. It is therefore common practice for a vehicle to be equipped with several balls of different sizes. This necessitates the positioning of the balls laterally or vertically. The positioning of the line of thrust transversely or vertically is undesirable because the load bearing vehicle will not be properly positioned behind the pulling vehicle.